The claimed invention relates to a shaft support in a tube for an engine-powered tool, for example a clearing saw or a trimmer, and a method for assembling the shaft support in the tube.
A number of different types of engine powered tools are used in order to facilitate work in forests and gardens. One type of tool that is used to increase the range of action and improve the working conditions for the operator is clearing saws, trimmers and similar tools where the working tool is placed in the end of a tube.
The tools have different working tools but all of them have the same configuration with the engine placed in one end of the tube and the working tool in the other. The length of the tube is adapted depending on the work that the tool is used for. For example is the length of the tube on a grass trimmer selected so that the operator will be able to walk upright with the working tool in suitable height over the ground while a tool for pruning of trees have a longer tube so that the operator will be able to reach the top of the tree standing on the ground. Some tools have a straight tube while some have a curved tube in order to adapt the angle of the working tool to the surface that will be worked and to improve the range of action for the tool.
Since the engine is placed in one end of the tube and the working tool in the other must the power from the engine be transferred to the working tool. This is done by a stiff or flexible drive shaft that is running inside the tube from the engine to the working tool. If a straight tube is used is it possible to use a stiff or a flexible drive shaft while a curved tube requires a flexible drive shaft, normally made of a flexible wire or a line.
In order to reduce the amount of vibrations and sound generated by the drive shaft in the tube and also to reduce the wear and risk for failure is the drive shaft supported in the tube. The vibrations and sound is generated if the drive shaft is allowed to move in radial direction inside the tube.
There are a number of different shaft supports used today. All of them are pressed into the tube whit the drive shaft placed in its right position in the support. In the patent documents DE383954SC2, U.S. Pat. No. 5,839,961A, U.S. Pat. No. 5,364,307A and U.S. Pat. No. 5,175,932A are some of the different types of shaft support where the drive shaft is placed in a circular section in the center of the shaft support. Different types of curved of angled support arms extends outwards from the circular section in order to support the circular section and the drive shaft in the tube. The support arms curved shape is a result of a compromise that will facilitate the assembling of the shaft support and the drive shaft in the tube since the curved arms are allowed to bend towards the circular section which makes it possible to press the shaft support and the drive shaft into the tube. When the shaft support and the drive shaft in its right position will the curved arms return to their normal position resting against the inside of the tube so that the circular section and the drive shaft are supported.
The existing shaft supports all have the drawback that the supporting arms that are shaped to facilitate the assembling also makes it possible for the circular section and the drive shaft to move in radial direction during use. These movements means that the support of the drive shaft not is satisfying since the movements will generate vibrations and sound.
There is therefor a need for improved shaft supports for drive shafts running inside a tube so that the amount of vibrations and sound generated from the drive shaft during use are reduced.